Mensagem original de: Annette Flottwell ,
I would suggest the same as Dan says. Hold the Shift-Control-Option on the left side of the keyboard '''for at least 10 seconds''' otherwise it doesn't work. If this doesn't help, check the symptoms for the MagSafe DC-In Board. Maybe that is your problem. Very important, you don't say which system you are running. When I installed Yosemite or El Capitan, it was going onto Icloud all the the time, wasting bandwidth and energy. My internet access is metered here in Costa Rica so I dumped the 'improved' systems and reinstalled 10.8.5. Result: more battery, less waste of internet and better performance altogether.